Phenotype-Genotype Correlation Applying a Cocktail Approach and an Exome Chip Analysis Reveals Further Variants Contributing to Variation of Drug Metabolism

Although great progress has been made in the fine-tuning of diplotypes, there is still a need to further improve the predictability of individual phenotypes of pharmacogenetically relevant enzymes. The aim of this study was to analyze the additional contribution of sex and variants identified by exome chip analysis to the metabolic ratio of five probe drugs. A cocktail study applying dextromethorphan, losartan, omeprazole, midazolam, and caffeine was conducted on 200 healthy volunteers. CYP2D6, 2C9, 2C19, 3A4/5, and 1A2 genotypes were analyzed and correlated with metabolic ratios. In addition, an exome chip analysis was performed. These SNPs correlating with metabolic ratios were confirmed by individual genotyping. The contribution of various factors to metabolic ratios was assessed by multiple regression analysis. Genotypically predicted phenotypes defined by CPIC discriminated very well the log metabolic ratios with the exception of caffeine. There were minor sex differences in the activity of CYP2C9, 2C19, 1A2, and CYP3A4/5. For dextromethorphan (CYP2D6), IP6K2 (rs61740999) and TCF20 (rs5758651) affected metabolic ratios, but only IP6K2 remained significant after multiple regression analysis. For losartan (CYP2C9), FBXW12 (rs17080138), ZNF703 (rs79707182), and SLC17A4 (rs11754288) together with CYP diplotypes, and sex explained 50% of interindividual variability. For omeprazole (CYP2C19), no significant influence of CYP2C:TG haplotypes was observed, but CYP2C19 rs12777823 improved the predictability. The comprehensive genetic analysis and inclusion of sex in a multiple regression model significantly improved the explanation of variability of metabolic ratios, resulting in further improvement of algorithms for the prediction of individual phenotypes of drug-metabolizing enzymes.

The Landé factors of electrons and holes in lead halide perovskites: universal dependence on the band gap

The Landé or g-factors of charge carriers are decisive for the spin-dependent phenomena in solids and provide also information about the underlying electronic band structure. We present a comprehensive set of experimental data for values and anisotropies of the electron and hole Landé factors in hybrid organic-inorganic (MAPbI₃, MAPb(Br_0.5Cl_0.5)₃, MAPb(Br_0.05Cl_0.95)₃, FAPbBr₃, FA_0.9Cs_0.1PbI_2.8Br_0.2, MA=methylammonium and FA=formamidinium) and all-inorganic (CsPbBr₃) lead halide perovskites, determined by pump-probe Kerr rotation and spin-flip Raman scattering in magnetic fields up to 10 T at cryogenic temperatures. Further, we use first-principles density functional theory (DFT) calculations in combination with tight-binding and k ⋅ p approaches to calculate microscopically the Landé factors. The results demonstrate their universal dependence on the band gap energy across the different perovskite material classes, which can be summarized in a universal semi-phenomenological expression, in good agreement with experiment.

The Landé factors govern all the spin-related basic phenomena and are the key parameters which guide spintronics applications. Here, Kirstein et al. demonstrate a universal dependence of the Landé factors on the bandgap energy of several perovskite materials.

Forced-air warming and continuous core temperature monitoring with zero-heat-flux thermometry during cesarean section: a retrospective observational cohort study

Background

Over 30% of parturients undergoing spinal anesthesia for cesarean section become intraoperatively hypothermic. This study assessed the magnitude of hypothermic insult in parturients and newborns using continuous, high-resolution thermometry and evaluated the efficiency of intraoperative forced-air warming for prevention of hypothermia.

Methods

One hundred and eleven parturients admitted for elective or emergency cesarean section under spinal anesthesia with newborn bonding over a 5-month period were included in this retrospective observational cohort study. Patients were divided into two groups: the passive insulation group, who received no active warming, and the active warming group, who received convective warming through an underbody blanket. Core body temperature was continuously monitored by zero-heat-flux thermometry and automatically recorded by data-loggers. The primary outcome was the incidence of hypothermia in the operating and recovery room. Neonatal outcomes were also analyzed.

Results

The patients in the passive insulation group had significantly lower temperatures in the operating room compared to the actively warmed group (36.4°C vs. 36.6°C, p = 0.005), including temperature at skin closure (36.5°C vs. 36.7°C, p = 0.017). The temperature of the newborns after discharge from the postanesthetic care unit was lower in the passive insulation group (36.7°C vs. 37.0°C, p = 0.002); thirteen (15%) of the newborns were hypothermic, compared to three (4%) in the active warming group (p < 0.01).

Conclusion

Forced-air warming decreases perioperative hypothermia in parturients undergoing cesarean section but does not entirely prevent hypothermia in newborns while bonding. Therefore, it can be effectively used for cesarean section, but special attention should be given to neonates.

Prevention of inadvertent perioperative hypothermia - Guideline compliance in German hospitals

Patients undergoing elective surgery are at risk for inadvertent postoperative hypothermia, defined as a core body temperature below 36°C. This study was conducted to investigate the acceptance of the recommendations of the German S3 Guideline, in particular with respect to the concept of pre-warming and sublingual temperature measurement. The main focus was to gather data concerning the postoperative core temperature and the frequency of perioperative hypothermia in patients receiving a pre-warming regime and those without. The study team investigated the local concept and measures employed to avoid inadvertent perioperative hypothermia with respect to defined outcome parameters following a specific protocol. In summary, the study hospitals vary greatly in their perioperative processes to prevent postoperative hypothermia. However, each hospital has a strategy to prevent hypothermia and was more or less successful in keeping its patients normothermic during the perioperative process. Our data could not demonstrate major differences between hospitals in the implementation strategy to prevent perioperative hypothermia in regard to the hospital size. The results of our study suggest a wide-spread acceptance, as no postoperative hypothermia was detected in a cohort of 431 patients.

Thermal reduction of ceria nanostructures on rhodium(111) and re-oxidation by CO2

The thermal reduction of cerium oxide nanostructures deposited on a rhodium(111) single crystal surface and the re-oxidation of the structures by exposure to CO2 were investigated. Two samples are compared: a rhodium surface covered to ≈60% by one to two O-Ce-O trilayer high islands and a surface covered to ≈65% by islands of four O-Ce-O trilayer thickness. Two main results stand out: (1) the thin islands reduce at a lower temperature (870-890 K) and very close to Ce2O3, while the thicker islands need higher temperature for reduction and only reduce to about CeO1.63 at a maximum temperature of 920 K. (2) Ceria is re-oxidized by CO2. The rhodium surface promotes the re-oxidation by splitting the CO2 and thus providing atomic oxygen. The process shows a clear temperature dependence. The maximum oxidation state of the oxide reached by re-oxidation with CO2 differs for the two samples, showing that the thinner structures require a higher temperature for re-oxidation with CO2. Adsorbed carbon species, potentially blocking reactive sites, desorb from both samples at the same temperature and cannot be the sole origin for the observed differences. Instead, an intrinsic property of the differently sized CeOx islands must be at the origin of the observed temperature dependence of the re-oxidation by CO2.

Growth and structure of ultrathin praseodymium oxide layers on ruthenium(0001)

The growth, morphology, structure, and stoichiometry of ultrathin praseodymium oxide layers on Ru(0001) were studied using low-energy electron microscopy and diffraction, photoemission electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. At a growth temperature of 760 °C, the oxide is shown to form hexagonally close-packed (A-type) Pr₂O₃(0001) islands that are up to 3 nm high. Depending on the local substrate step density, the islands either adopt a triangular shape on sufficiently large terraces or acquire a trapezoidal shape with the long base aligned along the substrate steps.

[Prevention of Perioperative Hypothermia - Guidelines for Daily Clinical Practice]

Inadvertent perioperative hypothermia (body core temperature < 36 °C) is a serious complication leading to increased rates of wound infection, higher blood loss associated with increased transfusion requirements as well as patient dissatisfaction among others. Body core temperature is a vital parameter and needs constant monitoring just like heart rate, blood pressure and arterial oxygen saturation. Patient-, anesthesia-, surgery- and environment-related risk factors were identified for occurring perioperative hypothermia.The avoidance of perioperative hypothermia requires a multidisciplinary approach for both medical and assistant staff. A bundle of procedures has to be arranged in order to improve patient outcome. Steps include general (e.g. staff instruction), pre- (e.g. prewarming), intra- (e.g. active warming) and postoperative (e.g. drug therapy) actions. An effective concept for prevention of perioperative hypothermia has to be adjusted to departments' specific constructional, organizational, process-related and staff characteristics with clearly visible and assigned responsibilities.

The cubic-to-hexagonal phase transition of cerium oxide particles: dynamics and structure

Cerium oxide is often applied in today's catalysts due to its remarkable oxygen storage capacity. The changes in stoichiometry during reaction are linked to structural modifications, which in turn affect its catalytic activity. We present a real-time in situ study of the structural transformations of cerium oxide particles on ruthenium(0001) at high temperatures of 700 °C in ultra-high vacuum. Our results demonstrate that the reduction from CeO₂ to cubic Ce₂O₃ proceeds via ordered intermediary phases. The final reduction step from cubic to hexagonal Ce₂O₃ is accompanied by a lattice expansion, the formation of two new surface terminations, a partial dissolution of the cerium oxide particles, and a massive mass transport of cerium from the particles to the substrate. The conclusions allow for new insights into the structure, stability, and dynamics of cerium oxide nanoparticles in strongly reducing environments.

Nanoscale analysis of the oxidation state and surface termination of praseodymium oxide ultrathin films on ruthenium(0001)

The complex structure and morphology of ultrathin praseodymia films deposited on a ruthenium(0001) single crystal substrate by reactive molecular beam epitaxy is analyzed by intensity-voltage low-energy electron microscopy in combination with theoretical calculations within an ab initio scattering theory. A rich coexistence of various nanoscale crystalline surface structures is identified for the as-grown samples, notably comprising two distinct oxygen-terminated hexagonal Pr₂O₃(0001) surface phases as well as a cubic Pr₂O₃(111) and a fluorite PrO₂(111) surface component. Furthermore, scattering theory reveals a striking similarity between the electron reflectivity spectra of praseodymia and ceria due to very efficient screening of the nuclear charge by the extra 4f electron in the former case.

Dynamic Variables Fail to Predict Fluid Responsiveness in an Animal Model With Pericardial Effusion

OBJECTIVES

The reliability of dynamic and volumetric variables of fluid responsiveness in the presence of pericardial effusion is still elusive. The aim of the present study was to investigate their predictive power in a porcine model with hemodynamic relevant pericardial effusion.

DESIGN

A single-center animal investigation.

PARTICIPANTS

Twelve German domestic pigs.

INTERVENTIONS

Pigs were studied before and during pericardial effusion. Instrumentation included a pulmonary artery catheter and a transpulmonary thermodilution catheter in the femoral artery. Hemodynamic variables like cardiac output (COPAC) and stroke volume (SVPAC) derived from pulmonary artery catheter, global end-diastolic volume (GEDV), stroke volume variation (SVV), and pulse-pressure variation (PPV) were obtained.

MEASUREMENTS AND MAIN RESULTS

At baseline, SVV, PPV, GEDV, COPAC, and SVPAC reliably predicted fluid responsiveness (area under the curve 0.81 [p = 0.02], 0.82 [p = 0.02], 0.74 [p = 0.07], 0.74 [p = 0.07], 0.82 [p = 0.02]). After establishment of pericardial effusion the predictive power of dynamic variables was impaired and only COPAC and SVPAC and GEDV allowed significant prediction of fluid responsiveness (area under the curve 0.77 [p = 0.04], 0.76 [p = 0.05], 0.83 [p = 0.01]) with clinically relevant changes in threshold values.

CONCLUSIONS

In this porcine model, hemodynamic relevant pericardial effusion abolished the ability of dynamic variables to predict fluid responsiveness. COPAC, SVPAC, and GEDV enabled prediction, but their threshold values were significantly changed.

OpenVigil FDA - Inspection of U.S. American Adverse Drug Events Pharmacovigilance Data and Novel Clinical Applications

Pharmacovigilance contributes to health care. However, direct access to the underlying data for academic institutions and individual physicians or pharmacists is intricate, and easily employable analysis modes for everyday clinical situations are missing. This underlines the need for a tool to bring pharmacovigilance to the clinics. To address these issues, we have developed OpenVigil FDA, a novel web-based pharmacovigilance analysis tool which uses the openFDA online interface of the Food and Drug Administration (FDA) to access U.S. American and international pharmacovigilance data from the Adverse Event Reporting System (AERS). OpenVigil FDA provides disproportionality analyses to (i) identify the drug most likely evoking a new adverse event, (ii) compare two drugs concerning their safety profile, (iii) check arbitrary combinations of two drugs for unknown drug-drug interactions and (iv) enhance the relevance of results by identifying confounding factors and eliminating them using background correction. We present examples for these applications and discuss the promises and limits of pharmacovigilance, openFDA and OpenVigil FDA. OpenVigil FDA is the first public available tool to apply pharmacovigilance findings directly to real-life clinical problems. OpenVigil FDA does not require special licenses or statistical programs.

Growth and characterization of epitaxially stabilized ceria(001) nanostructures on Ru(0001)

We have studied (001) surface terminated cerium oxide nanoparticles grown on a ruthenium substrate using physical vapor deposition. Their morphology, shape, crystal structure, and chemical state are determined by low-energy electron microscopy and micro-diffraction, scanning probe microscopy, and synchrotron-based X-ray absorption spectroscopy. Square islands are identified as CeO2 nanocrystals exhibiting a (001) oriented top facet of varying size; they have a height of about 7 to 10 nm and a side length between about 50 and 500 nm, and are terminated with a p(2 × 2) surface reconstruction. Micro-illumination electron diffraction reveals the existence of a coincidence lattice at the interface to the ruthenium substrate. The orientation of the side facets of the rod-like particles is identified as (111); the square particles are most likely of cuboidal shape, exhibiting (100) oriented side facets. The square and needle-like islands are predominantly found at step bunches and may be grown exclusively at temperatures exceeding 1000 °C.

Preventing inadvertent perioperative hypothermia

BACKGROUND

25-90% of all patients undergoing elective surgery suffer from inadvertent postoperative hypothermia, i.e., a core body temperature below 36°C. Compared to normothermic patients, these patients have more frequent wound infections (relative risk [RR] 3.25, 95% confidence interval [CI] 1.35-7.84), cardiac complications (RR 4.49, 95% CI 1.00-20.16), and blood transfusions (RR 1.33, 95% CI 1.06-1.66). Hypothermic patients feel uncomfortable, and shivering raises oxygen consumption by about 40%.

METHODS

This guideline is based on a systematic review of the literature up to and including October 2012 and a further one from November 2012 to August 2014. The recommendations were developed and agreed upon by representatives of five medical specialty societies in a structured consensus process.

RESULTS

The patient's core temperature should be measured 1-2 hours before the start of anesthesia, and either continuously or every 15 minutes during surgery. Depending on the nature of the operation, the site of temperature measurement should be oral, naso-/oropharyngeal, esophageal, vesical, or tympanic (direct). The patient should be actively prewarmed 20-30 minutes before surgery to counteract the decline in temperature. Prewarmed patients must be actively warmed intraoperatively as well if the planned duration of anesthesia is longer than 60 minutes (without prewarming, 30 minutes). The ambient temperature in the operating room should be at least 21°C for adult patients and at least 24°C for children. Infusions and blood transfusions that are given at rates of >500 mL/h should be warmed first. Perioperatively, the largest possible area of the body surface should be thermally insulated. Emergence from general anesthesia should take place at normal body temperature. Postoperative hypothermia, if present, should be treated by the administration of convective or conductive heat until normothermia is achieved. Shivering can be treated with medications.

CONCLUSION

Inadvertent perioperative hypothermia can adversely affect the outcome of surgery and the patient's postoperative course. It should be actively prevented.

Accuracy of an autocalibrated pulse contour analysis in cardiac surgery patients: a bi-center clinical trial

BACKGROUND

Less-invasive and easy to install monitoring systems for continuous estimation of cardiac index (CI) have gained increasing interest, especially in cardiac surgery patients who often exhibit abrupt haemodynamic changes. The aim of the present study was to compare the accuracy of CI by a new semi-invasive monitoring system with transpulmonary thermodilution before and after cardiopulmonary bypass (CPB).

METHODS

Sixty-five patients (41 Germany, 24 Spain) scheduled for elective coronary surgery were studied before and after CPB, respectively. Measurements included CI obtained by transpulmonary thermodilution (CITPTD) and autocalibrated semi-invasive pulse contour analysis (CIPFX). Percentage changes of CI were also calculated.

RESULTS

There was only a poor correlation between CITPTD and CIPFX both before (r (2) = 0.34, p < 0.0001) and after (r (2) = 0.31, p < 0.0001) CPB, with a percentage error (PE) of 62 and 49 %, respectively. Four quadrant plots revealed a concordance rate over 90 % indicating an acceptable correlation of trends between CITPTD and CIPFX before (concordance: 93 %) and after (concordance: 94 %) CPB. In contrast, polar plot analysis showed poor trending before and an acceptable trending ability of changes in CI after CPB.

CONCLUSIONS

Semi-invasive CI by autocalibrated pulse contour analysis showed a poor ability to estimate CI compared with transpulmonary thermodilution. Furthermore, the new semi-invasive device revealed an acceptable trending ability for haemodynamic changes only after CPB.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02312505 Date: 12.03.2012.

Ketamine in outpatient arthroscopic shoulder surgery: Effects on postoperative pain, hemodynamic stability and process times

Background

Pain after arthroscopic shoulder surgery is often severe, and establishing a pain treatment regimen that does not delay discharge can be challenging. The reported ability of ketamine to prevent opioid-induced hyperalgesia has not been investigated in this particular setting.

Methods

300 adult patients scheduled for shoulder arthroscopy under general anesthesia were recruited for this observational clinical trial and were allotted to either receive 1mg/kg IV bolus of ketamine before surgery (ketamine group, KG) or to a control group (CG) without ketamine. NRS pain scores were obtained on the operative day and on postoperative days 1 and 2 and compared between groups. Secondary variables were blood pressure, heart rate, process times, satisfaction with the anesthetic and unwanted effects.

Results

Pain severity did not differ significantly between the groups at any time. Propofol injection rate and cumulative dose were higher in the KG. Heart rates and blood pressures were similar. Time to emergence and time in PACU were longer and vomiting was more frequent in patients given ketamine.

Conclusion

Preoperative low-dose ketamine added to a general anesthetic does not reduce perioperative pain after outpatient shoulder arthroscopy. It increases procedural times and the incidence of PONV.

[Robot-assisted surgery in visceral and thoracic surgery gynaecology, urology--importantanaesthetic considerations]

Robot-assisted surgery, as a development of laparoscopic surgery, has an increasing field of application. Beside urology, this technique has also been implemented in visceral and thoracic surgery and gynaecology. For the surgeon an enhanced view of the surgical field and a better mobility of the instruments are the most important advantages. Thus, it is possible to work more accurate and prevent inadvertent tissue damage. For the anaesthesiologist several characteristics are of importance. Limited access to the patient as a result of a special positioning requires adequate anaesthetic preparation. For many visceral and thoracic surgical interventions the head and airway of the patient is bedded remote from the anaesthesiologist. Therefore, a standardised order and protection of all i. v.-lines, cables and the ventilation-hose of the (double-lumen) tube is essential. After the roboter is connected to the patient, it is nearly impossible to change or extend patient monitoring. Especially in case of emergency, e. g. respiratory complications or heart failure, a close communication with the surgeon and a team approach are indispensable.

Surface resonances in electron reflection from overlayers

Electron scattering by oxygen monolayers on the Ru(0 0 0 1) surface is studied both experimentally and theoretically. Sharp transmission resonances at low energies are revealed and established to originate from critical points of a special kind in the complex band structure of the substrate. Electron reflection from the clean and oxidized Ru(0 0 0 1) is measured for kinetic energies up to 40 eV at normal incidence for oxygen coverages of 1/4, 1/2, 3/4, and one monolayer. The reflection spectra R(E) are analyzed using a Bloch-waves based ab initio scattering theory. In addition to the substrate-induced resonances the reconstructed (2 × 1) and (2 × 2) surfaces show surface resonances due to pre-emergent secondary diffraction beams. The R(E) spectra are shown to give unambiguous evidence of the hcp stacking of the oxygen layer.

The incidence and prevention of hypothermia in newborn bonding after cesarean delivery: a randomized controlled trial

BACKGROUND

Little is known about thermoregulation of the newborn while bonding on the mother's chest immediately after cesarean delivery. Newborn hypothermia is associated with serious complications and should be avoided. Therefore, we evaluated whether newborns develop hypothermia during intraoperative bonding while positioned on their mothers' chests and investigated the effects of active cutaneous warming of the mothers and babies during a 20-minute intraoperative bonding period.

METHODS

We enrolled 40 parturients scheduled for elective cesarean delivery under spinal anesthesia. Mothers and their newborns were randomized to receive either passive insulation or forced-air skin-surface warming during the surgical procedure and bonding period. The primary outcome was neonatal core temperature at the end of the bonding period. Core temperatures of the newborns were measured with a rectal probe. Body temperatures of the mothers were assessed by sublingual measurements. Skin temperatures, thermal comfort of the mothers, and perioperative shivering were evaluated.

RESULTS

Without active warming from the beginning of the surgical procedure until the end of the bonding period, the mean (SD) neonatal core temperature decreased to 35.9 (0.6)°C. Seventeen of 21 (81%) newborns became hypothermic (defined as a core temperature below 36.5°C). Active skin-surface warming from the beginning of the surgical procedure until the end of the bonding period resulted in a neonatal core temperature of 37.0 (0.2)°C and a decreased incidence of hypothermia (1 of 19 (5%) newborns (P < 0.0001)). In addition, active warming increased the mean skin temperatures of the infants, maternal core and skin temperatures, maternal thermal comfort, and reduced perioperative shivering.

CONCLUSIONS

Active forced-air warming of mothers and newborns immediately after cesarean delivery reduces the incidence of infant and maternal hypothermia and maternal shivering, and increases maternal comfort.

[Organisation and scheduling of interhospital intensive care patient transport]

The need for interhospital transfer of intensive care and high risk patients is increasing. These transfers are dangerous and challenging. Successful organisation and scheduling includes the appropriate selection of the transport vehicle and the preliminary consultation and cooperation of all participants according to predefined rules. This article describes definitions and fundamentals, specific characteristics of different transport vehicles, recommended consultation and typical pitfalls.

Influence of nociceptive stimulation on analgesia nociception index (ANI) during propofol-remifentanil anaesthesia

BACKGROUND

Measurement of the balance between nociception and anti-nociception during anaesthesia is challenging and not yet clinically established. The Surgical pleth index (SPI), derived from photoplethysmography, was proposed as a surrogate measure of nociception. Recently, the analgesia nociception index (ANI) derived by heart rate (HR) variability was developed. The aim of the present study was to challenge the ability of ANI compared with SPI to detect standardized noxious stimulation during propofol-remifentanil anaesthesia.

METHODS

After Ethics approval and informed consent, 25 patients were anaesthetized with propofol [bispectral index (BIS) 30-60]. A laryngeal mask (LMA) was inserted and remifentanil stepwise increased to effect-site concentrations (Ce(remi)) of 0, 2, and 4 ng ml(-1). At each step, tetanic stimulation (STIM) was applied. ANI, SPI, BIS, HR, and mean arterial pressure (MAP) were obtained before and after LMA insertion and each STIM. Analysis was performed using Wilcoxon rank tests and calculation of prediction probabilities (P(K)).

RESULTS

ANI and SPI, but not BIS, HR, or MAP, were significantly (P<0.05) changed at all examined steps. ANI response to STIM was (median [IQR]) -24 [-12-35], -30 [-20 - -40] and -13 [-5 - -27] at 0, 2 and 4 ng ml(-1) Ce(remi). However, prediction of movement to STIM was not better than by chance, as P(K) values were 0.41 (0.08) for ANI and 0.62 (0.08) for SPI.

CONCLUSIONS

The two variables, ANI and SPI, enabled consistent reflection of stimulation during propofol-remifentanil anaesthesia. Nevertheless, ANI and SPI may improve detection but not prediction of a possible inadequate nociception-anti-nociception balance. Clinicaltrials.gov Identifier. NCT01522508.

Correlation of surgical pleth index with stress hormones during propofol-remifentanil anaesthesia

Eighty patients undergoing elective ear-nose-throat surgery were enrolled in the present study to investigate the relationship between surgical pleth index (SPI) and stress hormones (ACTH, cortisol, epinephrine, norepinephrine) during general anaesthesia which was induced and maintained with propofol and remifentanil using a target-controlled infusion. The study concluded that the SPI had moderate correlation to the stress hormones during general anaesthesia, but no correlation during consciousness. Furthermore, SPI values were able to predict ACTH values with high sensitivity and specificity.

[Xenon anaesthesia--clinical characteristics, benefits and disadvantages and fields of application]

The noble gas xenon provides many characteristics of the 'ideal anaesthetic agent'. Xenon offers outstanding haemodynamic stability and rapid emergence from anaesthesia without relevant side effects or toxity. The major limitation for its application in clinical routine is the high price. Recent studies demonstrated additional protective effects against ischaemic injury in particular for the heart and the brain. Therefore, xenon may be beneficial in a subset of high risk patients or operations and may become a meaningful alternative to other anaesthetics in this population.

The shaker potassium channel is no target for xenon anesthesia in short-sleeping Drosophila melanogaster mutants

Background. Xenon seems to be an ideal anesthetic drug. To explore if next to the antagonism at the NMDA-receptor other molecular targets are involved, we tested the xenon requirement in short sleeping Drosophila shaker mutants and in na[har³⁸]. Methods. The Drosophila melanogaster strains wildtype Canton-S, na[har³⁸], sh¹⁰² and sh^mns, were raised and sleep was measured. Based on the response of the flies at different xenon concentrations, logEC50 values were calculated. Results. The logEC50-values for WT Canton-S were 1.671 (1.601–1.742 95%-confidence intervall; n = 238; P versus sh¹⁰² > 0,05), for sh^mns 1.711 (1.650–1.773; n = 242; P versus WT Canton-S > 0,05). The logEC50-value for sh¹⁰² was 1.594 (1.493–1.694; n = 261; P versus sh^mns > 0.05). The logEC-value of na[har³⁸] was 2.076 (1.619–2.532; n = 207; P versus sh^mns < 0.05, versus sh¹⁰² < 0.05, versus WT Canton-S < 0.05). P values for all shaker mutants were P > 0.05, while na[har³⁸] was found to be hyposensitive compared to wildtype (P < 0.05). Conclusions. The xenon requirement in Drosophila melanogaster is not influenced by a single gene mutation at the shaker locus, whereas a reduced expression of a nonselective cation channel leads to an increased xenon requirement. This supports the thesis that xenon mediates its effects not only via an antagonism at the NMDA-receptor.

Accuracy of the pleth variability index to predict fluid responsiveness depends on the perfusion index

BACKGROUND

Respiratory variations in plethysmographic waveform amplitudes derived from pulse oximetry are believed to predict fluid responsiveness. The non-invasive pleth variability index (PVI) is a variable based on the calculation of changes in the perfusion index (PI). The aim of the following study was to examine whether the predictive power of PVI depends on different values of PI.

METHODS

Eighty-one patients undergoing elective coronary artery surgery were studied before operation: at baseline after induction of anaesthesia and during passive leg raising (PLR). Each patient was monitored with central venous pressure (CVP), the PiCCO monitor and the non-invasive Masimo monitoring system. Stroke volume index by transpulmonary thermodilution (SVI(TPTD)), pulse pressure variation (PPV), stroke volume variation (SVV) and systemic vascular resistance index (SVRI) were measured using the PiCCO monitoring system. PI and PVI were obtained by pulse oximetry.

RESULTS

Responders were defined to increase their SVI(TPTD) >15% after PLR. The highest area under the curve (AUC) was found for PPV (AUC: 0.83, P<0.0001) and SVV (AUC: 0.72, P=0.002), in contrast to PVI (AUC: 0.60, P=0.11) and CVP (AUC: 0.60, P=0.13). The accuracy of PVI to predict fluid responsiveness was improved on analysing patients with higher PI values. PI of about 4% (n=45) achieved statistical significance (AUC: 0.72, P=0.01).

CONCLUSION

The PVI was not able to predict fluid responsiveness with sufficient accuracy. In patients with higher perfusion states, the PVI improved its ability to predict haemodynamic changes, strongly suggesting a relevant influence of the PI on the PVI.

Uncalibrated pulse power analysis fails to reliably measure cardiac output in patients undergoing coronary artery bypass surgery

Introduction

Uncalibrated arterial pulse power analysis has been recently introduced for continuous monitoring of cardiac index (CI). The aim of the present study was to compare the accuracy of arterial pulse power analysis with intermittent transpulmonary thermodilution (TPTD) before and after cardiopulmonary bypass (CPB).

Methods

Forty-two patients scheduled for elective coronary surgery were studied after induction of anaesthesia, before and after CPB respectively. Each patient was monitored with the pulse contour cardiac output (PiCCO) system, a central venous line and the recently introduced LiDCO monitoring system. Haemodynamic variables included measurement of CI derived by transpulmonary thermodilution (CI_TPTD) or CI derived by pulse power analysis (CI_PP), before and after calibration (CI_PPnon-cal., CI_PPcal.). Percentage changes of CI (ΔCI_TPTD, ΔCI_{PPnon-cal./PPcal.}) were calculated to analyse directional changes.

Results

Before CPB there was no significant correlation between CI_PPnon-cal. and CI_TPTD (r² = 0.04, P = 0.08) with a percentage error (PE) of 86%. Higher mean arterial pressure (MAP) values were significantly correlated with higher CI_PPnon-cal. (r² = 0.26, P < 0.0001). After CPB, CI_PPcal. revealed a significant correlation compared with CI_TPTD (r² = 0.77, P < 0.0001) with PE of 28%. Changes in CI_PPcal. (ΔCI_PPcal.) showed a correlation with changes in CI_TPTD (ΔCI_TPTD) only after CPB (r² = 0.52, P = 0.005).

Conclusions

Uncalibrated pulse power analysis was significantly influenced by MAP and was not able to reliably measure CI compared with TPTD. Calibration improved accuracy, but pulse power analysis was still not consistently interchangeable with TPTD. Only calibrated pulse power analysis was able to reliably track haemodynamic changes and trends.

Assessment of left ventricular systolic function during acute myocardial ischemia: a comparison of transpulmonary thermodilution and transesophageal echocardiography

BACKGROUND

The PiCCO system provides different variables of cardiac function: the cardiac function index (CFI), the global ejection fraction (GEF) and the maximal pressure developed by the left ventricle (dP/dtMax). The purpose of this study was to investigate the ability of these variables to predict impaired left ventricular ejection fraction (LVEF) derived by transesophageal echocardiography during acute myocardial ischemia.

METHODS

In this prospective experimental study, fifteen pigs (28-34 kg) were anesthetized, mechanically ventilated and subjected to left anterior descending (LAD) coronary artery occlusion. PiCCO-derived variables and LVEF were obtained 5, 10, 15, and 20 minutes after LAD occlusion. Receiver operating characteristics analysis was performed to assess the ability of PiCCO-derived parameters to estimate LVEF ≤40% and ≤50%.

RESULTS

LAD occlusion induced a decrease in PiCCO-derived variables and LVEF (P<0.001 for each). Significant correlations were found between LVEF and CFI (r=0.59, P<0.001), GEF (r=0.64, P<0.001), dP/dtMax (r=0.36, P<0.001), and cardiac output (r=0.25, P=0.028). The area under the receiver operating characteristics curve for the estimation of LVEF ≤40% and ≤50% was 0.80 and 0.79 for CFI (P=0.009, P<0.001), 0.86 and 0.78 for GEF (P=0.002, P<0.001), 0.76 and 0.68 for dP/dtMax (P=0.033, P=0.012), and 0.57 and 0.58 for cardiac output (P=0.554, P=0.259).

CONCLUSION

Cardiac function indices permit the bedside quantification of left ventricular systolic function during acute myocardial ischemia in pigs. Therefore, the PiCCO system may represent a valuable technique for cardiovascular monitoring, particularly for detecting acute left ventricular systolic dysfunction due to myocardial ischemia.

Surgical stress index in response to pacemaker stimulation or atropine

BACKGROUND

The surgical stress index (SSI) is a new monitoring tool for the assessment of nociception during general anaesthesia. It is calculated based on the heart beat interval and the pulse wave amplitude. Correlation of SSI with nociceptive stimuli and opioid effect-site concentrations has been demonstrated, but the influence of isolated modulation of heart rate (HR) on SSI is still unclear. The aim of this study was to evaluate the effect on SSI of atropine administration and cardiac pacing.

METHODS

In 18 anaesthetized ASA III ICU patients, either repetitive cardiac pacemaker stimulation or administration of atropine (10 microg kg(-1)) was performed, and the effect on SSI, arterial pressure, spectral entropy, and bispectral index was analysed.

RESULTS

Cardiac pacing at 100 beats min(-1) was followed by an increase in SSI from 26 [17-35 (10-41)] to 59 [53-72 (48-78)] {median [inter-quartile range (range)]} (P=0.0006), whereas other variables remained unaffected. Also, atropine administration increased SSI from 27 [20-34 (16-39)] to 58 [48-70 (41-81)] (P=0.007) without significant effect on other variables except HR. A recalibration of SSI during cardiac pacing leads to a significant decrease in SSI to 49 [40-52 (36-57)] (P=0.03), whereas recalibration after atropine administration had no effect.

CONCLUSIONS

SSI values measured in patients receiving atropine or in patients with pacemakers should be interpreted cautiously.

Correlation and agreement between the bispectral index vs. state entropy during hypothermic cardio-pulmonary bypass

BACKGROUND

The bispectral index (BIS) and spectral entropy enable monitoring the depth of anaesthesia. Mild hypothermia has been shown to affect the ability of electroencephalography monitors to reflect the anaesthetic drug effect. The purpose of this study was to investigate the effect of hypothermia during a cardio-pulmonary bypass on the correlation and agreement between the BIS and entropy variables compared with normothermic conditions.

METHODS

This prospective clinical study included coronary artery bypass grafting patients (n=25) evaluating correlation and agreement (Bland-Altman analysis) between the BIS and both spectral and response entropy during a hypothermic cardio-pulmonary bypass (31-34 degrees C) compared with nomothermic conditions (34-37.5 degrees C). Anaesthesia was maintained with propofol and sufentanil and adjusted clinically, while the anaesthetist was blinded to the monitors.

RESULTS

The BIS and entropy values decreased during cooling (P<0.05), but the decrease was more pronounced for entropy variables compared with BIS (P<0.05). The correlation coefficients (bias+/-SD; percentage error) between the BIS vs. spectral state entropy and response entropy were r(2)=0.56 (1+/-11; 42%) and r(2)=0.58 (-2+/-11; 43%) under normothermic conditions, and r(2)=0.17 (10+/-12; 77%) and r(2)=0.18 (9+/-11; 68%) under hypothermic conditions, respectively. Bias was significantly increased under hypothermic conditions (P<0.001 vs. normothermia).

CONCLUSION

Acceptable agreement was observed between the BIS and entropy variables under normothermic but not under hypothermic conditions. The BIS and entropy variables may therefore not be interchangeable during a hypothermic cardio-pulmonary bypass.

Interaction of morphine but not fentanyl with cerebral α2-adrenoceptors in α2-adrenoceptor knockout mice

Objectives

α2-Adrenergic and μ-opioid receptors belong to the rhodopsin family of G-protein coupled receptors and mediate antinociceptive effects via similar signal transduction pathways. Previous studies have revealed direct functional interactions between both receptor systems including synergistic and additive effects. To evaluate underlying mechanisms, we have studied whether morphine and fentanyl interacted with α2-adrenoceptor-subtypes in mice lacking one individual α2-adrenoceptor-subtype (α2-adrenoceptor knockout).

Methods

Opioid interaction with α2-adrenoceptors was investigated by quantitative receptor autoradiography in brain slices of α2A-, α2B- or α2C-adrenoceptor deficient mice. Displacement of the radiolabelled α2-adrenoceptor agonist [125I]paraiodoclonidine from α2-adrenoceptors in different brain regions by increasing concentrations of morphine, fentanyl and naloxone was analysed. The binding affinity of both opioids to α2-adrenoceptor subtypes in different brain regions was quantified.

Key findings

Morphine but not fentanyl or naloxone provoked dose-dependent displacement of [125I]paraiodoclonidine from all α2-adrenoceptor subtypes in the brain regions analysed. Binding affinity was highest in cortex, medulla oblongata and pons of α2A-adrenoceptor knockout mice.

Conclusions

Our results indicated that morphine interacted with α2-adrenoceptors showing higher affinity for the α2B and α2C than for the α2A subtype. In contrast, fentanyl and naloxone did not show any relevant affinity to α2-adrenoceptors. This effect may have an impact on the pharmacological actions of morphine.

[Anaesthesia management of the obese patient]

Obesity is a global epidemic, and approximately 20 % of the German population are obese. Therefore anaesthesiologists will be increasingly involved in the care of obese and morbidly obese patients in the near future. As a prerequisite, the hospital must focus on this patient population with respect to facilities and the availability of tailored medical equipment and supplies. Comorbidities such as diabetes, hypertension, coronary heart disease and sleep apnea considerably increase the risk of obese patients. A thorough preoperative evaluation of comorbidities, an anaesthesia induction and intraoperative ventilation tailored to the pathophysiological sequelae of obesity and a sound knowledge of pharmokocinetics are necessary to ensure optimal care for obese patients.

Nefopam but not physostigmine affects the thermoregulatory response in mice via alpha(2)-adrenoceptors

Nefopam, a non-opioid, centrally acting benzoxazocine analgesic, proved to be as efficient in treatment of postanaesthetic thermoregulatory shivering as clonidine or meperidine. However, its exact mechanism of action is still unclear. Potent anti-shivering activity was also demonstrated for physostigmine primarily based on cholinergic but probably also different additional mechanisms of action. Hypothesizing an involvement of alpha(2)-adrenoceptors we studied their role in nefopam- and physostigmine-mediated thermoregulation in a mouse model of nonshivering thermogenesis. To differentiate possible alpha(2)-adrenoceptor subtype-specific interactions, we analysed wildtype mice and mice with deletion of the alpha(2A)-, alpha(2B)- or alpha(2C)-adrenoceptor (knock out). Ten mice of each genotype (n = 40) were administered saline, saline plus atipamezole, 1 mg/kg nefopam, 25 mg/kg nefopam, 25 mg/kg nefopam plus atipamezole, physostigmine and physostigmine plus atipamezole intraperitoneally. Each mouse was randomly subjected to each of the seven different treatments. Afterwards, the mice were positioned into a plexiglas chamber where rectal temperature and mixed expired carbon dioxide were measured during following whole body cooling. Thermoregulatory threshold temperature of nonshivering thermogenesis and maximum response intensity were analysed. Nefopam decreased the thermoregulatory threshold temperature in wildtype, alpha(2B)- and alpha(2C)-adrenoceptor mice. This effect was partially abolished by additional administration of the alpha(2)-adrenoceptor antagonist atipamezole. In alpha(2A)-adrenoceptor knock out mice, nefopam did not affect the thermoregulatory threshold. In contrast, physostigmine decreased the thermoregulatory threshold in wildtype and all alpha(2)-adrenoceptor knock out mice independently from additional atipamezole administration. Our results indicate an important role of the alpha(2A)-adrenoceptor in the thermoregulatory response induced by nefopam but not by physostigmine in mice.

Interaction of morphine but not fentanyl with cerebral alpha2-adrenoceptors in alpha2-adrenoceptor knockout mice

OBJECTIVES

alpha(2)-Adrenergic and mu-opioid receptors belong to the rhodopsin family of G-protein coupled receptors and mediate antinociceptive effects via similar signal transduction pathways. Previous studies have revealed direct functional interactions between both receptor systems including synergistic and additive effects. To evaluate underlying mechanisms, we have studied whether morphine and fentanyl interacted with alpha(2)-adrenoceptor-subtypes in mice lacking one individual alpha(2)-adrenoceptor-subtype (alpha(2)-adrenoceptor knockout).

METHODS

Opioid interaction with alpha(2)-adrenoceptors was investigated by quantitative receptor autoradiography in brain slices of alpha(2A)-, alpha(2B)- or alpha(2C)-adrenoceptor deficient mice. Displacement of the radiolabelled alpha(2)-adrenoceptor agonist [(125)I]paraiodoclonidine from alpha(2)-adrenoceptors in different brain regions by increasing concentrations of morphine, fentanyl and naloxone was analysed. The binding affinity of both opioids to alpha(2)-adrenoceptor subtypes in different brain regions was quantified.

KEY FINDINGS

Morphine but not fentanyl or naloxone provoked dose-dependent displacement of [(125)I]paraiodoclonidine from all alpha(2)-adrenoceptor subtypes in the brain regions analysed. Binding affinity was highest in cortex, medulla oblongata and pons of alpha(2A)-adrenoceptor knockout mice.

CONCLUSIONS

Our results indicated that morphine interacted with alpha(2)-adrenoceptors showing higher affinity for the alpha(2B) and alpha(2C) than for the alpha(2A) subtype. In contrast, fentanyl and naloxone did not show any relevant affinity to alpha(2)-adrenoceptors. This effect may have an impact on the pharmacological actions of morphine.

Influence of different remifentanil concentrations on the performance of the surgical stress index to detect a standardized painful stimulus during sevoflurane anaesthesia

BACKGROUND

Although measurement of cerebral hypnotic drug effect and muscle relaxation is common clinical routine during anaesthesia, a reliable measurement of the neurophysiological effects evoked by a painful stimulus is still missing. Recently, the surgical stress index (SSI) has been introduced as a surrogate measure of 'nociception'. The present study aimed to examine the influence of increasing remifentanil concentrations on the ability of SSI to detect a standardized painful stimulus during sevoflurane anaesthesia.

METHODS

Twenty-four patients received incremental or decremental doses of 0, 2, and 4 ng ml(-1) remifentanil effect-site concentration (Ce(remi)) during 0.7 MAC sevoflurane. Painful tetanic stimulation was applied at least 5 min after changing Ce(remi). SSI, heart rate (HR), response entropy (RE), state entropy (SE), RE-SE difference, and bispectral index (BIS) were obtained in each patient before and after stimulation. Further prediction of an author-defined response to painful stimulus was analysed.

RESULTS

SSI and BIS, but not HR, SE, RE, or RE-SE difference were significantly altered after stimulation. Change in SSI (Delta SSI) was significantly dependent on Ce(remi), as Delta SSI was [median (inter-quartile range)] 20 (15-31), 10 (1-19), and 3 (1-10) at 0, 2, and 4 ng ml(-1) Ce(remi). In 10 out of 63 cases, SSI detected response to stimulation, not detected by another variable. SSI was unable to predict movement after stimulation as P(K) value is 0.59 (0.09).

CONCLUSIONS

The SSI response to tetanic stimulation was dependent on the remifentanil concentration.

Reliability of continuous cardiac output measurement during intra-abdominal hypertension relies on repeated calibrations: an experimental animal study

INTRODUCTION

Monitoring cardiac output (CO) may allow early detection of haemodynamic instability, aiming to reduce morbidity and mortality in critically ill patients. Continuous cardiac output (CCO) monitoring is recommended in septic or postoperative patients with high incidences of intra-abdominal hypertension (IAH). The aim of the present study was to compare the agreement between three CCO methods and a bolus thermodilution CO technique during acute IAH and volume loading.

METHODS

Ten pigs were anaesthetised and instrumented for haemodynamic measurements. Cardiac output was obtained using CCO by pulse power analysis (PulseCO; LiDCO monitor), using CCO by pulse contour analysis (PCCO; PiCCO monitor) and using CCO by pulmonary artery catheter thermodilution (CCOPAC), and was compared with bolus transcardiopulmonary thermodilution CO (COTCP) at baseline, after fluid loading, at IAH and after an additional fluid loading at IAH. Whereas PulseCO was only calibrated at baseline, PCCO was calibrated at each experimental step.

RESULTS

PulseCO and PCCO underestimated CO, as the overall bias +/- standard deviation was 1.0 +/- 1.5 l/min and 1.0 +/- 1.1 l/min compared with COTCP. A clinically accepted agreement between all of the CCO methods and COTCP was observed only at baseline. Whereas IAH did not influence the CO, increased CO following fluid loading at IAH was only reflected by CCOPAC and COTCP, not by uncalibrated PulseCO and PCCO. After recalibration, PCCO was comparable with COTCP.

CONCLUSIONS

The CO obtained by uncalibrated PulseCO and PCCO failed to agree with COTCP during IAH and fluid loading. In the critically ill patient, recalibration of continuous arterial waveform CO methods should be performed after fluid loading or before a major change in therapy is initiated.

Propofol/remifentanil vs sevoflurane/remifentanil for long lasting surgical procedures: a randomised controlled trial

We compared the haemodynamics, emergence and recovery characteristics of total intravenous anaesthesia using propofol/remifentanil with sevoflurane/remifentanil anaesthesia, under bispectral index guidance, in 103 patients undergoing surgical procedures lasting > 3.5 h. Time to tracheal extubation was significantly shorter in the propofol group than in the sevoflurane group (mean (SD) 8.3 (3.5) min vs 10.8 (4.6) min, respectively; p = 0.0024), but further recovery was comparable in both groups. There were no significant differences in haemodynamic parameters, intensity of pain or postoperative nausea and vomiting. During and after anaesthesia of comparable depth for long lasting surgical procedures, both propofol/remifentanil and sevoflurane/remifentanil enable haemodynamic stability and fast emergence. The shorter time to extubation in the propofol group does not offer a relevant clinical advantage.